1. Field of the Invention
This invention relates generally to subsurface tools used in the completion of subterranean wells and, more particularly, provides an apparatus and method for use in spacing out tubular strings and components within a wellbore.
2. Description of Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, i.e., a reservoir, by drilling a well that penetrates a hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, the production of oil and gas can begin.
Typically, one of the final steps taken in the completion of a well is the running into the well of the production tubing. Once the production tubing is inserted into the well, the bottom of the tubing string may need to be located at a certain position in relation to other downhole equipment, such as being inserted into a polished bore receptacle of a packer that had been previously set. Just as the bottom of the tubing string needs to be located in a predetermined depth, likewise the top of the tubing string has to be located so as to properly xe2x80x9clandxe2x80x9d the tubing hanger within the wellhead. In order for both the top and bottom of the tubing string to be in their proper locations, the length of the tubing string is measured and controlled. This operation is called the xe2x80x9cspacing outxe2x80x9d of the well.
For wells drilled on land, the spacing out of the production tubing is a relatively simple task. The tubing is run into the well to the depth of the packer until contact with the packer is indicated by a decrease in the weight of the tubing string. At a predetermined xe2x80x9cslack offxe2x80x9d weight, the tubing is marked and measured. The upper joint of tubing is removed and replaced with one or more shorter tubing sections, often called xe2x80x9csubsxe2x80x9d, that will make the overall tubing string the length needed for the proper well space out. Since the wellhead, completion unit and personnel are located at the surface, the spacing out of the tubing string is usually a minor task.
On wells that are drilled offshore that contain a subsea wellhead, the operation of spacing out a well can be difficult. The wellhead where the tubing must be landed is located on the ocean floor, not where the rig and personnel are located. For wells being completed from fixed platforms, the distance from the rig floor to the wellhead can be measured and compensated for. One method is to run the tubing into the well until the required slack off weight is seen. Then rather than just the top joint being removed, the length of tubing from the rig floor to the wellhead on the ocean floor must be pulled to enable the proper space out to be made. After the proper adjustments are made and the tubing hanger is attached, the modified tubing string length will be run back into the well. For example, a well drilled in a water depth of 2,000 feet that needs an adjustment of 10 feet for proper space out, would require the pulling and subsequent re-running of the 2,000 feet of tubing, for a total handling of 4,000 feet of tubing. Alternately, the tubing hanger can be attached to the tubing string on the initial run into the well at a location that is estimated to be correct. If the location is within the variance of the downhole tool, such as the length of the polished bore receptacle, the tubing will not need to be pulled and adjusted. Using specialized tools, such as packers with longer than usual polished bore receptacles and tubing seal assemblies with extra length and multiple seals, will increase the possibility of success with this alternate method, but will also increase the material cost incurred.
Wells being completed from floating drilling rigs such as semisubmersibles or drillships pose additional problems. The xe2x80x9cheavexe2x80x9d of the floating rig, along with variations in the positioning of the rig over the well, results in the distance from the rig floor to the wellhead not being a fixed length (i.e., being a variable length). This length can vary by as much as three feet or more, depending on tidal and wave conditions, which can make the methods of spacing out mentioned above unworkable, difficult or time consuming to perform. The amount of heave can also vary depending on the age, design and level of sophistication of the rig positioning system. To compensate for the rig heave, additional equipment, such as expansion joints, sliding sleeves, extended seal assembly lengths and multiple seals have been employed.
There is a need for improved tools and methods to enable the proper spacing out of offshore wells.
One embodiment of the present invention is a system for use in spacing components within a wellbore. The system comprises a well casing comprising at least one profile, the profile capable of being positioned at a known location within the wellbore and adapted to indicate the location of at least one component inserted into the wellbore.
Another embodiment of the present invention comprises an apparatus for use in spacing out tubular strings within a well comprising a casing having an inner wall where the casing includes at least one profile disposed within the inner wall. A landing tool is linked to well tubing and is sized so as to seat within the profile. A tubing hanger is attached to the well tubing, the tubing hanger being capable of landing within a wellhead. When the landing tool is seated within the profile, the length of well tubing needed to land the tubing hanger within the wellhead can be determined. The tubing string can be inserted within the well. The distance between the wellhead and the profile can be known.
The casing can comprise an upper profile and a lower profile and the distance between the upper profile and the lower profile can be known. The landing tool and the upper profile are capable of being in a releasably seated configuration.
Yet another embodiment of the invention can be used for the spacing out of tubular strings within a well that comprises a casing having an inner wall, the casing comprising an upper profile and a lower profile. A well tubing is movable longitudinally within the casing and a landing tool is linked to the well tubing. The landing tool can comprise seating projections that are adapted to sequentially seat in the upper profile and the lower profile. The landing tool and seating projections can be adapted to reversibly seat in the upper profile, allowing movement of the landing tool in either an upward or downward direction. The landing tool, seating projections and lower profile can be adapted such that when the landing tool is seated within the lower profile, the landing tool is restricted from any movement in a downward direction but can be unseated from the lower profile and moved in an upward direction. The landing tool and seating projections can be adapted to release from the upper profile when a predetermined slack off weight is exceeded. When the landing tool is seated within the upper profile, the length of well tubing needed to space out the well tubing can be determined.
Still another embodiment of the invention is a method of spacing components within a wellbore. The method comprises providing a well casing comprising at least one profile and inserting at least one component within the wellbore wherein at least one component can releasably engage with the at least one profile. The effects of the engagement of at least one component with the at least one profile are observed and the amount of component movement required to obtain a desired component placement within the wellbore is determined.
An alternate embodiment of the invention is a method of spacing out a tubular string within a well having a wellhead. This method comprises providing a casing string located within the well, the casing string having an inner wall and at least one profile within the casing inner wall. The casing can include an upper profile, and the profiles can be located at known distances apart from each other and from the wellhead. A tubular string linked to a landing tool is inserted into the well. The landing tool is seated within the upper profile and the correct tubular length required to properly space out the well is determined. The steps in the method can include attaching the landing tool to the tubular string to be spaced out and the landing tool can be capable of seating within the profiles. The method can further include inserting the tubular string to a depth where the landing tool seats within the upper profile, unseating the landing tool from the upper profile, modifying the length of the tubular string, attaching a tubing hanger to the tubular string and inserting the tubular string into the well to a depth where the tubing hanger is disposed within the wellhead.
When the tubing hanger is disposed within the wellhead, the landing tool can be seated within one of the profiles other than the upper profile. The well can further comprise a packer set within the casing string and the tubular string can further comprise a seal assembly capable of being seated within the packer.
Yet another embodiment of the invention is a method of spacing out a tubing string within a wellhead of an offshore well comprising providing a casing string having a first profile, inserting a tubing string within the well having a landing tool that can engage with the first profile, inserting the tubing string until the landing tool engages with the first profile. The length of tubing string needed for proper tubing space out can then be determined, the landing tool disengaged from the first profile, and the tubing string altered to achieve a predetermined length. A tubing hanger is then attached to the tubing string and the tubing string inserted to the depth where the tubing hanger is properly positioned within the wellhead.
The well can further comprise a packer set within the casing string and the tubular string can further comprise a seal assembly and the seal assembly can be capable of being seated within the packer. The disengaging of the landing tool from the first profile can be achieved by imposing a predetermined slack off weight onto the tubing string.
The casing string can comprise a second profile and when the tubing hanger is positioned within the wellhead, the tubing string can be spaced out so that the landing tool is engaged with the second landing profile. The landing tool in conjunction with the second landing profile can be capable of radially orienting the tubing string in relation to the casing string. The tubing string can contain an extension tool that allows the extension of the tubing string below the landing tool. The extension tool can enable the extension of more than one tubing string below the landing tool. The well can comprise at least one lateral wellbore and two tubing strings extend from the extension tool and the two tubing strings each enter separate wellbores.
Still another embodiment of the invention is a method of completing a well comprising providing a well casing comprising at least one profile on its inner wall and inserting the well casing within a wellbore comprising at least one lateral wellbore. At least one component is inserted within the wellbore on a tubular string, the at least one component comprising at least one landing tool that can releasably engage with the at least one profile. The effects of the engagement of at least one landing tool with the at least one profile are observed and the amount of tubular string movement required to obtain a desired component placement within the wellbore is determined.
Another embodiment is a method of completing a well comprising providing a well casing comprising at least one profile on its inner wall and inserting the well casing into a wellbore, the wellbore comprising at least one lateral wellbore. At least one landing tool that can releasably engage with the at least one profile is inserted into the wellbore on a tubular string, the at least one landing tool comprising at least one lower tubing string capable of extending from the at least one landing tool. The effects of the engagement of at least one landing tool with the at least one profile are observed and the amount of tubular string movement required to obtain a desired component placement within the wellbore is determined, the desired component placement comprising the landing of a tubing hanger within a wellhead. At least one lower tubing string is extended from the extension member into at least one lateral wellbore.